Electromagnetic vibratory interrupter



Auga 3958 c. HUETTEN ET AL 2,49,63

ELECTROMAGNETIC VIBRATORY INTERRUPTER Filed Nov. 10, 1954 warm ffaellew ams [flan/mam Mlhlaw Egg 519w INVENTORS ATTORNEY 2,849,563 ELECTROMAGNETIC vInRAToRY INTERRUPTER Clarence Huetten. and James J. Kaufmann, Indianapolis, and William E. Rigsbee, Shelbyville, Ind., assignors to P. R. Mallory & 60., line, Indianapolis, Ind, a corporation of Delaware Application November 10, 1954, Serial No. 468,090

11 Claims. (Cl. 200-90) This invention relates to vibrators, and, more particularly, to electromagnetic vibratory interrupters of novel and improved character.

Conventional vibrators generally comprise a vibratory reed having a pair of reed arms mounted thereon and a pair of side arms having one of their ends fixed and their free ends extending into cooperating relation with the ends of the reed arms. Contact discs, generally made of tungsten, are secured to the free ends of the reed and side arms and are adapted to make and break one or more electric circuits during vibrations of the reed. Driving means, usually in the form of a driver coil, are provided for maintaining the reed in continuous vibration, said coil being under the control of the reed and side arm contacts or under control of a separate pair of contacts operated by the reed.

Although vibrators of the described character have been manufactured on a very large scale for a number of years, considerable practical difiiculties have been experienced in their operation. The contacts in the form of relatively thick and heavy discs at the ends of the reed and side arms concentrated a very substantial amount of mass at such ends. This increased the impact losses and thus made it necessary to introduce a large amount of driving power, most of which was detrimentally, or at least uselessly, dissipated at the time when the mating contacts struck against each other. Normally, when a contact mass is suspended on the end of a compliant arm and is set in motion, free oscillations are produced, such oscillations being of sufllcient amplitude and velocity that the arm and contact must be either tuned, stopped, or damped. Tuning of the vibrator arms necessitates critical parts selection, while stopping or damping such arms requires a more complex structure, increasing the cost of the vibrator quite considerably.

Other disadvantages connected with the manufacture and operation of conventional vibrators were that the heavy disc-shaped contacts had to be very accurately spaced from each other for optimum operation. Even slight changes in the contact spacing, due to erosion and wear, would seriously interfere with the operating efliciency and would even cause the vibrator to stop operating altogether. The brazing material interposed between the tungsten and the steel spring arm interfered with heat and electrical conduction and was the frequent cause of operating difliculties. Welding or brazing of the contact discs to the springs was a relatively expensive procedure and required careful inspection to eliminate the danger of imperfect attachment.

It Was already suggested to combine the supporting spring and the contact in a single mechanical element by plating the steel spring with a suitable contact metal, such as silver, which cooperates with a conventional disc-shaped contact. While contact systems of this type constituted an improvement, particularly in high-frequency vibrators, they required that the vibrator be polarized. Also, the thin layer of contact metal on the spring would wear off or erode within a short time, exposing the underlying surface of the base metal of poor contact characteristics. For this reason, contacts nited States Patent of this type have been practical for light duty applications only and even there reduced the useful life of the vibrator quite considerably. Although various-other suggestions and proposals were made to solve the outstanding problem, none, as far as we are aware, of these suggestions and proposals, were completely satisfactory and successful on a practical and commercial scale.

We have discovered that the problem may be solved in a simple and completely satisfactory manner.

It is an object of the present invention to improve electromagnetic vibratory interrupters.

It is another object of the present invention to provide a novel and improved vibrator in which the contact spring and the contact itself are integrally formed from a single leaf or strip of contact metal.

It is a further object of the invention to provide a vibratory interrupter comprising switching means in the form of a pair of cooperating molybdenum leaf springs, the body portions of which constitute compliant arms and the end portions of which constitute contacts adapted to make and break an electric circuit during operation of said interrupter.

It is also Within the contemplation of the invention to provide a novel vibratory interrupter comprising combination side arms, reed arms and contacts of molybdenum leaf which is simple in construction, reliable in operation, capable of handling substantial amounts of power, and which may be readily manufactured and sold at a low cost on a practical and commercial scale.

The invention also contemplates a split'reed vibrator of novel and improved character which preferably incorporates molybdenurnleaf spring contacts.

Other and further objects and advantages of the invention will become apparent from the following de-.

scription, taken in conjunction with the accompanying drawing, in which:

Fig. 1 is a front elevational View of a vibrator of the splitreedtype embodying the principles of the present invention;

Fig. 2 is a side elevational view of the vibrator shown in Fig. 1; and

. Fig. 3 is an exploded detail view of the vibratory system of the vibrator shown in Figs. 1 and 2.

Broadly stated, in accordance with the principles of the present invention, we provide a vibrator in which the reedarms and side arms are formed of molybdenum leaf springs, the end portions of which directly constitute cooperating cont-acts. A vibrator of this type is characterized by a very light vibratory mass which, in combination with the other unexpected advantages following from the use of molybdenum, results in a structure which is in practically all respects superior to conventional vibrators employing relatively heavy discshaped contacts welded or brazed to steel springs.

While the advantages of light mass in vibrators were probably first observed on high frequencyvibrators, it has since become apparent that such advantages are also present in lower frequency vibrators, such as in commercial vibrators operating at frequencies of about cycles.

The energy required to drive a vibrator is directly related to the losses of the mechanism. The majority of the losses, the losses due to contact impact, are shown by the equation:

where M=mass of contacts and effective portions ofcontact supports 7 V=velocity of contacts just before impact I K=energy represented as impact losses It becomes obvious from the above equation that the driving power is directly proportonal to the contact mass. It has been quite diflicult in the past to increase the life and the load handling ability of a vibrator without making the vibrator correspondingly larger. In other words, simply making the conventional, heavy, disc-shaped con tacts larger, unfortunately increases the driving power required for a given contact spacing and frequency and consequently generally increases the size of the vibrator. The use of molybdenum leaf as a combination spring and contact material, as provided by the present invention, is of considerable importance since it permits designing vibrators smaller in size for the same load handling ability or no bigger in size than conventional vibrators but with much increased load handling ability and longer life. It is no longer necessary to employ useless contact arms and supports as it was unavoidable with conventional contacts, the mass of which was not usable as a contact eroding material and therefore was dead weight requiring additional power to drive it. In accordance with the invention, the ends of the reed arms and side springs-where the mass counts most from an energy standpointcan be entirely used as a contact material and the spring then serves a dual purpose, that is, a spring and a contact.

It is well known to those skilled in the vibrator art that vibrators operate at the resonant frequency of their moving mass and the compliance of the system. Molybdenum springs, whether used as reed arms, side arms, or both, become a part of this mass and compliance. Good design practice utilizes the contacting area to the best advantage. Since the part is fabricated by conventional dies from a sheet of molybdenum, the area of the contacting surface and the thickness of the material is chosen to give correct spring constants, determined principally by its thickness. The contacting surface is then designed in such shape and area as is desirable for life and free oscillation considerations. One of the very important factors is the ability to design for more area and volume than conventional contacts. The ideal result is that there is much less spacing change and therefore less output voltage drop as life progresses than in conventional vibrators. Generally, vibrators of conventional design are rarely able to utilize more than .010 in. thickness of the contact material supplied, whereas in most cases it is necessary to make the contact disc at least 0.020 in. thick for practical fabrication purposes. This is an extremely important advantage in favor of the molybdenum leaf spring, as it can be fabricated in the most economical thickness and the excess mass of unused contact material, support arms, etc., characteristic of conventional vibrator structures, are not present in this type of vibrator mechanism, which results in substantial savings in the size and cost of the vibrator.

Molybdenum has certain characteristics which make it excellently suited for a combination contact and spring. Among these characteristics are its extremely high melting point (2620 C.) and boiling point (3700 C.). The high melting point and the high boiling point render the material quite resistant to erosion due to arcing. Another desirable feature of molybdenum in direct current contact applications is the fact that metal transfer is minimized due to the formation and volatilization of molybdenum oxide. A further advantage of molybdenum is its low density which is considerably less than that of conventional tungsten contact materials. Molybdenum is readily available in strip form and its physical properties are such that springs made from molybdenum have very desirable charactertistics. It has a high modulus of elasticity, approximately 42,000,000 p. s. i. This means that quite high forces can be developed with very little deflection. Tensile strengths range from 85,000 1:. s. i. up to as high as 155,000 or 160,000 p. s. i., depending upon the amount of cold working. Yield strengths at .2% ofiset range in the neighborhood of 90% of the ultimate tensile strength. The desirable physical characteristics from the standpoint of a spring material and the desirable electrical contact characteristics make it an ideal material for vibrator contact springs. Its use eliminates the necessity of making a complicated assembly involving a contact, such as tungsten, attached to a spring.

In actual practice, it has been found that molybdenum strip having a wide range of physical properties gives satisfactory performance. For instance, material has been used satisfactorily when the tensile strength was as low as 102,000 p. s. i. with an elongation of 17% in 2 in. Material with a tensile strength of 154,000 p. s. i. and an elongation of only 4% in 2 in. has also been found to work very well. For best performance, however, it has been established that material having an ultimate strength from 115,000 to 125,000 p. s. i. with an elongation of 10% to 15% is desirable. It is important to use material which has not been recrystallized, since, in general, recrystallized molybdenum is quite brittle and has low ductility and low fatigue strength. Material which has been cold worked and then given a stress relief anneal has been found to be very satisfactory. Such a material still shows the cold worked structure resulting from cold rolling. The grains are fibrous and elongated. Such a structure permits forming the material into the necessary shape without fracture and also results in high fatigue strength which is important in vibrator applications where the springs are subjected to millions of operations.

The new results and important advantages obtainable by the principles of the present invention may be summarized as follows:

1) The use of molybdenum leaf as a combination spring and contact greatly reduces the mass of the vibratory system. This in turn reduces the impact losses and the power that is required to drive the vibrator. For example, heavy duty vibrators capable of carrying currents in the order of 20 to 30 amperes can be readily driven at 115 cycles and may be built in relatively small sizes, whereas conventional vibrators of similar power handling ability operate at about to cycles.

(2) The contact areas may be made quite large, without appreciably increasing the mass that has to be reciprocated. Thus, the contacts can handle heavy current, while remaining quite cool, so that contact transfer and erosion are greatly reduced.

With molybdenum leaf spring contacts, there is considerable latitude in the design of the arms for economical use of the contact material, as well as to provide, with a part of the same thickness, a suitable reed arm or side arm. The arm can be designed thin and the contacting area large so that the normal erosion of the material with use causes much less spacing change with life. This is an important feature, as the output voltage then drops at a much lower average rate than in conventional vibrators. This is due to the much slower spacing change with life permitting the time efficiency also to change at the lower rate. The output voltage is proportional to the vibrator time efliciency. The slow spacing change with life due to the large contact area design, made possible by the light mass of the arms and flexible design possibilities, then causes the output voltage to drop off with life at a much lower rate than in conventional vibrators.

(3) In good vibrator design, high compliance is needed in the reed arms or side arms. This gives the vibrator high time efficiency characteristics. Certain practical limitations determine the maximum amount of compliance which can be given to a single arm. With the molybdenum leaf arms of the present invention, compliance can be constructed in both the reed arms and side anns providing substantial improvement in the operation of the vibrator.

(4) Conventional vibrators often fail because contact erosion causes the spacings to increase beyond the serves. no useful purpose except to hold the contact.

When the contact area is increased to decrease the spacing change, the resulting increase in mass is very diflicult to drive. With molybdenum leaf springs it is not at all difficult to drive the amount of contact mass needed for good contact life. Much less mass is needed at the end of the arms to get the needed contact surface area. Also, since the mass at the end' of the arms is less, the arm can be made more compliant without getting undue amplitude of free arm oscillations.

In most conventional vibrators, contact spacings are generally quite inflexible. There is a conflict between the desire on one part to make the contact spacings as wide as practical to enable the production adjustment to be easier and the design engineer on the other hand is immediately confronted with the size limitations continually imposed on him. The size of a vibrator is related to the contact spacings, since the driving requirements are proportional to the square of the spacings. The size of a vibrator then is proportional to the driving power requirements. It can be easily seenthat, in conventional vibrators, the tendency invariably is toward closer and closer contact spacings to conserve the size of the vibrator. I

Since the effective mass of the reedarms and sid arms is much less when using molbdenum leaf springs, in the vibrators of the invention the spacings can be widened considerably for the same driving power re quirernents' that are available to conventional vibrators. It is also true that, if desired, a smaller vibrator can now be designed with spacings not wider than in conventional vibrators. Furthermore, as the driving power required (and consequently size) varies as the square of the spacings, it is readily apparent that conventional vibrators of conventional size require much more driving power in order to increase spacings without changing other important characteristics, such as life, time efficiency, output voltage, frequency, etc. The low effective mass of molybdenum leaf springs makes it possible to combine small size and wide contact spacings in a vibrator.

The contacts on most vibrators wear somewhat unevenly. In some instances this is due to the angle of contact make, however, in most cases the surface irregularities are due to erosion or contact migration phenomena. Sometimes there will develop a mound of material on one contact and a corresponding valley on its mating contact. Occasionally, the contact migration will form rapidly and take the shape of a long, thin spike of transfer. This kind of contact migration invariably causes trouble and vibrator failure. These long spikes of transfer can be formed when the thickness of the contact is sulficient to supply the material to build a transfer spike of such length.

When using molybdenum leaf springs as a combination arm and contact, the thickness can be so chosen that any transfer that might build up is always limited in height by the thickness of the arm. Preferably, the thickness is so selected as to be insufficient for building up a spike of transfer. Mound transfer, too, is limited to a safe value.

An important feature of the molybdenum leaf springs of the invention, then, is its natural ability, by correct design, to limit transfer and remove the usual cause of early life failure in vibrators. Conventional contacts are usually backed up by a steel table, a steel reed arm, or side arm, so that, when transfer goes through the contact material, it hits the steel backing and the result is immediate failure. Molybdenum leaf springs are not backed by any material in the contacting area and as a result are not subject. to this type of failure.

('6) Contact slide may be controlled somewhat by the amount. of compliance in the reed arm and side arm. Varying degrees of slide are needed in different vibrators. Too much slide may cause excessive wear and erosion, while no slide may result in transfer and oxidized contact surfaces. When the side arm is relatively stiff and the reed arm compliant, the reed arm contact moves up on the side arm contacts as they are deflected. When the reed arm is more stiff and the side arm more compliant, the reed arm contactslides down on the side arm. Since with the molybdenum leaf springs of the invention it is possible to distribute the compliance between the reed and side arms within awide range, the slide can be readily adjusted by choice of design tothe desired optimum value.

(7) Molybdenum leaf spring; contacts are more resistant to the detrimental efiects of heat because both the contacts, as Well as the supporting arms, are integrally formed of the same high. melting point material, which assures better heat flow away from the contact area. This is especially important in vibrator applications that are subject to severe starting flare. Contacts that are copper brazed to a steel reed arm will many times melt the copper bond and fall off. before a fuse will blow, should there be an abnormal. current flow due to a circuit difficulty or an unusual starting flare. The molybdenum reed arms of the invention are generally not damaged beyond use if the circuit is correctly fused. This necessarily follows from the high melting point of molybdenum, 2620 0, whereas the meltingv points of steel and copper are approximately 1500 C. and 1050 C., respectively.

(8) Since contact. and supporting arm are made integrally from molybdenum leaf or spring, the cost of separately fabricating a contact and securing it to an arm is eliminated. Also, the molybdenum leaf contacts of the invention. can be made. with various shapes and curvatures by means of stamping with far less difficulty than can aconventional contact.

(9) Since contact and arm are integrally formed, heat conduction and electrical conduction from the contact to the arm is not hinderedby a weld barrier that is interposed between a. conventional contact and arm.

(10) As a result of the integral construction of contact and arm, mechanical strength from contact to arm is inherently good and does not require inspection.

(11) One of the mostimportant advantages in using molybdenum leaf is the elimination of free oscillation diffculties of the reed arms and side arms. Normally, when a contact mass is suspended on the end of a compliance and set in motion, the oscillations are of suflicient amplitude and velocity that the arm and contact must be either tuned or they must be stopped or damped when they are used in a vibrator. When molybdenum leaf is used, there is no concentrated mass at the contact. This results in lower velocity and lower mass of the contact and lower impact losses. The can be tuned and the molybdenum stock can be. used as purchased to commercial tolerance without selection of thickness of the material. Vibrators operate very successfully when tuned with molybdenum leaf springs principally because of two reasons:

(a) The impact losses are low even when the vibrator gets slightly out of tune.

(b) The resonant frequency of the arm does not change appreciably with a change in thickness.

The principles of the present invention make it possible for the first time in the history of the art to provide the advantages of a tuned vibratory system in a vibrator by means of parts stamped out of sheets rolled to commercialtolerances, in contrast to conventional tuned vibrators in which the thickness or gauge of the arms was extremely critical and could be obtained only by means of costly parts selection.

(12) Molybdenum springs provide another very important advantage on 12 volt vibrators. With the present trend toward 12 volt electrical systems in automobiles, caution must be used in vibrators to prevent starting contact flare due to initial transformer saturation. It is Well known that wider contact spacings will help this situation. Since the driving power required varies as the square of the spacings, it becomes readily apparent that in conventional vibrators of the usual size, much more driving power must be supplied to increase spacings and I not change other characteristics of the circuit, such as life, time efficiency, output voltage, frequency, etc. Since the effective mass of the reed arms and side arms is much less than conventional vibrators, the spacings can be widened considerably for the same driving power requirements as are available to conventional vibrators.

in order that those skilled in the art may have a better understanding of the invention, a practical embodiment of the invention into a split reed vibrator will be described. This split reed vibrator incorporates certain novel features, in addition to the use of a molybdenum leaf spring, such as the particular structure used for insulating one-half of the reed from the other half.

Referring now more particularly to the drawing, reference numeral 10 denotes a hook-shaped ferromagnetic frame, having a stack 11 at one end and a driver coil 12 around its other end 13, which constitutes a pole piece. In stack 11 are clamped between insulative spacers 14 and metal spacers 15 a reed 16 and spaced side arms 17 by means of bolts 18 and nuts 19. As it Will be best observed in Fig. 3, the reed, which is preferably formed of spring steel, has a ferromagnetic armature 20 attached to its free end and is provided with cut-outs 21 and 22 for purposes which will appear presently. In the lower region thereof, the reed is provided with a small and a large circular aperture, 23 and 24, respectively, which serve for attachment of the reed arms. A first hinge portion 25, with a stack screw aperture 26 is integrally formed with the reed, while the second hinge portion 2.7, with a stack screw aperture 28 and a second, smaller aperture 29 for the rivet securing one pair of the reed arms thereto, is formed as a separate piece. A pair of reed arms 30 and 31 are secured to the reed by means of a rivet 32 extending through aperture 23 of the reed and are electrically connected thereto. A second pair of reed arms 33 and 34 and second hinge portion 27 are also secured to the reed by means of a rivet 35 extending through aperture 24 of the reed but are electrically insulated therefrom by the interposition of insulative spacers 36 and 37 and also due to the fact that aperture 24 in the reed is sufficiently large so as to avoid electrical contact of rivet 35 with the reed. It will thus be noted that while the first pair of reed arms, 30, 31, is electrically connected to reed 16 and its first and integral hinge portion the second pair of reed arms, 33, 34, is electrically insulated from reed 16 and is electrically connected to the second, separate hinge portion 27. This novel structure for splitting the reed, or, in other words, for electrically insulating the two pairs of reed arms from each other, greatly reduces the number of parts needed, the assembly labor, and the total cost of the reed assembly as compared to the conventional split reed structures in which two completely independent reeds of similar shape are mechanically connected with but are electrically insulated from each other. In most cases, it is desirable to adjust the natural frequency of the reed arms so that such frequency is an integer multiple of the frequency of the reed, as this is disclosed in Brown Fatent No. 2,197,607.

The driver contact system comprises a generally T- shaped flipper 38 of spring steel, bearing a vibratory driver contact 39 -on the longitudinal center portion thereof and having a smaller and a larger aperture, 40 and 41, respectively, in its transverse portion. Flipper 38 is secured to the reed by the same rivets 32 and 35 that are used for securing the two parts of reed arms contact area capable of carrying heavy currents.

in such a manner that the flipper is electrically connected to the reed but is insulated from reed arms 33 and 34 and from the separate hinge portion 27. Vibratory driver contact 3? is arranged for cooperation with a stationary driver contact 42 mounted on one end of an arm 43, the other end of which is welded to frame 10, as shown at 44.

The reed and flipper are designed to complement each other for good operation. The flipper is preferably very compliant so as not to unduly bias the reed, it should support suflicient contact material for good driver contact life, it should not be overstressed and it should not oscillate unduly so as to cause contact bounce and hop-off.

The reed has been designed with as much taper, as defined by cut-outs 21 and 22, as is practical so as to eliminate overstressing when run at high amplitudes and high reed thickness. A greater reed thickness increases the energy storage in the reed for a given amplitude and weight. The reed has a cross bar 45 located at a point of low stress which helps to damp the flipper oscillations and also lifts the flipper off the contact for a fast contact separation. The flipper is designed to have a taper in width and pivot point such that very little rubbing and consequently Wear is present on the flipper and reed. It is also so constructed that any wear that occurs on the reed will not weaken the same.

Reed arms 30, 31 and 33, 34 and side arms 17 are formed of molybdenum leaf spring strips which are bent along a transverse line defining the arms of supporting portions from the contact portions thereof. The angle of the bend is so determined that in the normal position of the rest of the vibratory system, the cooperating contact portions of the respective arms are closely parallelspaced with respect to each other and provide a large Short slots 46 are cut out from side arms 17 and generally semicircular portions 47 are cut out from reed arms 30, 31, 33 and 34 in the region of the bend line to increase the compliance of the said arms in such region.

As the circuit employed in connection with the vibrator of the invention is the same as is used with conventional vibrators of the split reed type, the operation of our novel vibrator will be readily understood by those skilled in the art without any detailed description. The vibrator of the invention was found by actual test to be capable of handling currents as high as 23 amperes without any appreciable contact wear or erosion so that its useful life is as long or even longer than that of vibrators of the conventional type and of similar size handling a mere fraction of such heavy current load.

Although the present invention has been disclosed in connection with a preferred embodiment thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the invention. Thus, with very minor modifications in parts and adjustment, the vibrator of the invention can be made a duplex, split reed, self rectifier, and a self rectifier with rectifying contacts insulated from the interrupter contacts. It is further to be noted that the principles of the molybdenum leaf springs of the invention, constituting integrally formed reed or side arms and contacts, are not limited to split reed vibrators but are applicable with equal or similar results to vibrators of all types. All of these variations and modifications are considered to be within the true spirit and scope of the present invention, as disclosed in the foregoing description and defined in the appended claims.

What is claimed is:

1. A vibratory interrupter comprising, in combination, a reed having a first hinge portion integrally formed with an end portion thereof, a second hinge portion secured to said end portion of the reed and electrically insulated therefrom, a first pair of reed arms mechanically and electrically connected to said reed above said first hinge portion, a second pair of reed arms mounted on but electrically disconnected from said reed above and in electrical connection with said second hinge portion, and means for vibrating said reed.

2. A vibratory interrupter comprising, in combination, a reed having a first hinge portion integrally formed with an end portion thereof, a second hinge portion secured to said end portion of the reed and electrically insulated therefrom, a first pair of reed arms mechanically and electrically connected to said reed above said first hinge portion, a second pair of reed arms mounted on but electrically disconnected from said reed above and in electrical connection with said second hinge portion, said first and said second hinge portions, respectively, constituting electrical terminals for said two pairs of reed arms, a side arm for and in cooperative relation with each of said reed arms, a stack in which said hinge portions and said side arms are mounted, and means for maintaining said reed in vibration.

3. A split reed vibratory interrupter comprising, in combination, a reed having a first hinge portion integrally formed with an end portion thereof, a second hinge portion secured to said end portion of the reed but electrically insulated therefrom, a first pair of reed arms mechanically and electrically connected to said reed above said first hinge portion, a second pair of reed arms mounted on but electrically disconnected from said reed above and in electrical connection with said second hinge portion, a side arm for and in cooperative relation with each of said reed arms, each of said reed and side arms being formed of molybdenum leaf spring, a stack in which said hinge portions and said side arms are mounted, and means for maintaining said reed in vibration whereby cooperating portions of corresponding reed and side arms will alternately make and break an electrical circuit.

4. A split reed vibratory interrupter comprising, in

combination, a reed having a first hinge portion integrally formed with an end portion thereof, a second hinge portion secured to said end portion of the reed and electrically insulated therefrom, a first pair of reed arms mechanically and electrically connected to said reed above said first hinge portion, a second pair of reed arms mounted on but electrically disconnected from said reed above and in electrical connection with said second hinge portion, a side arm for and in cooperative relation with each of said reed arms, each of said reed and side arms being formed of molybdenum leaf spring, a stack in which said hinge portions and said side arms are mounted, a driver coil for said reed, and means including a flipper mounted on said reed bearing a vibratory driver contact and a relatively stationary driver contactv for controlling the circuit of said coil thereby to maintain said reed in vibration.

5. A split reed vibratory interrupter comprising, in combination, a hook-shaped ferromagnetic frame, a driver coil around the hook end of the frame, a stack on the other end of said frame, a reed having a first hinge portion integrally formed with an end portion thereof, a second hinge portion secured to said end portion of the reed and electrically insulated therefrom, a first pair of reed arms mechanically and electrically con-- nected to said reed above said first hinge portion, a second pair of reed arms mounted on but electrically disconnected from said reed above and in electrical con nection with said second hinge portion, a side arm for and in cooperative relation with each of said reed arms, said hinge portions and said side arms being clamped in said stack and the free end of said reed extending into cooperating relation with said driver coil, and means including a flipper on said reed bearing a vibratory driver contact and a relatively stationary driver contact 10 for controlling the circuit of said coil, thereby to maintain said reed in vibration.

6. The vibratory interrupter claimed in claim 5 Wherein each of the reed arms and side arms are formed of molybdenum leaf spring strips, the body portion of which constitutes a support for the arm and the end portion of which constitutes a contact of substantial area.

7. The vibratory interrupter claimed in claim 5 wherein said reed and side arms are formed of molybdenum leaf spring material, each of said arms having a first portion which extends substantially in the direction of the reed and a second portion which is bent at an angle with respect to said first portion, the second portions of the corresponding reed and side arms extending into closely parallel-spaced relation with respect to each other and being adapted to alternately make and break electrical circuits during vibrations of said reed.

8. The vibratory interrupter claimed in claim 2 wherein at least one of each pair of cooperating arms has cut out portions for increasing the compliance thereof and comprises a support portion and an integral contact portion bent at an angle with respect to the support portion, the contact portions of the corresponding reed and side arms extending into closely parallel-spaced relation with respect to each other and being adapted to contact each other over a large surface area during vibrations of the reed.

9. The vibratory interrupter claimed in claim 2 wherein the reed and side arms comprise a support portion and an integral contact portion bent at an angle with respect to the support portion, the contact portions of the corresponding reed and side arms extending into closely parallel-spaced relation with respect to each other and being adapted to contact each other over a large surface area during vibrations of the reed, said side arms having transverse slots and said reed arms having generally semi-circular portions cut out therefrom in the region of the bend line to increase the compliance thereof.

10. The vibratory interrupter claimed in claim 2 wherein the reed arms and the side arms are formed of cold-rolled molybdenum leaf spring material free from recrystallization, said spring material being characterized by elongated fibrous grains and having a tensile strength between 102,000 and 154,000 p. s. i.

11. The vibratory interrupter claimed in claim 2 wherein the reed arms and the side arms are formed of cold-rolled molybdenum leaf spring material free from recrystallization, said spring material being characterized by elongated fibrous grains and having a tensile strength between 115,000 and 125,000 p. s. i. and an elongation between 10% and 15% in 2 inches.

References Cited in the file of this patent UNITED STATES PATENTS 453,572 Baumann June 2, 1891 2,156,487 Barrett May 2, 1939 2,197,607 Brown Apr. 16, 1940 2,490,895 Aust et al. Dec. 13, 1949 2,519,730 Aust et al Aug. 22, 1950 2,519,731 Aust Aug. 22, 1950 2,600,247 Huetten June 10, 1952 2,606,259 Huetten Aug. 5, 1952 OTHER REFERENCES Publication: Fansteel Electrical Contacts, copyright 1950, by Fansteel Metallurgical Corp., North Chicago, Ill. (pages 10, 11 and 12). 

